Description: The overall objective of the Histology Core is to provide histopathology services, so that pathophysiological invesfigafions will be backed by quantitative morphological data The Core provides expertise and state-of-the-art technical services for histologic and cytologic analyses, and the data obtained are presented in a visual and/or quantitative format. The Histology Core is a continuation ofthe Celt,Tissue, and Imaging Core in the previous cycle. The Core has provided reliable imaging of lung cells and tissues, and will continue to provide this essential service in the revised application. Cells and cell components can be easily visualized [e.g.,neutrophils, T cells, and macrophages (and their granules), collagen, elastin, capillary endothelial cells and pericytes, and basement membranes]. The Core also keeps abreast of new developments in histopathology and helps participating faculty apply the appropriate techniques to their research projects. Finally, the Core helps the project leaders prepare images for publication and presentation. It is important to emphasize that this Core's services extend far beyond those of just producing tissue sections. The Core provides knowledge, expertise and interpretation ofthe histological and cytological preparations produced. It helps the investigators evaluate and design experiments that use these techniques. It also trains investigators, postdoctoral fellows, graduate students and technicians in animal necropsy, Tissue fixafion, histopathology, immunohistochemistry, in situ hybridizafion, and image analysis. The Core staff can also provide assistance in the development of histopathologic and morphometric techniques as new findings make them necessary. The Core thus provides a centralized way to insure that proper quantitative morphology is carried out by each of the three Projects. Several representative examples of the Core's work for current and new Project Leaders are shown in the Figures in secfion 6 below. Addifional examples are shown in the limited Preliminary Data secfions ofthe individual project descripfions. Current capabilities of the Core include the following: Embedding, sectioning and staining of paraffin sections for light microscopy. Performing light and electron microscopy and assistance in the interpretation of results Preparation of frozen specimens Performing enzyme histochemistry and immunohistochemistry and interpreting results Staining and analysis of cultured cells Fluorescent microscopy Photmicroscopy In situ hybridization Quantitative image analysis and image archiving The Cell and Tissue Analysis Core also performs quantitative morphometric analysis by means of two computers, both of which are equipped with Media Cybernetics Image Pro Plus image analysis software. This software allows quantification of cell numbers, vascular and airway perimeters, and several other variables as required by investigators. For all quantitative morphology, the Core will insure that all protocols, sampling, and analysis are consistent with the guidelines set forth in the new policy statement recently published by the American Thoracic Society (4). We also note that Dr. Mitzner was one of the 20 internafional scientists that met on two occasions to write this document as a collaborative author, and he will advise Dr. Gabrielson in proper stereologic procedures.